Thermodynamics of a Heat Engine - (First/Second Law)

[laser1]

Homework Statement

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Relevant Equations

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and the solutions:

I am not sure why two of the bodies are at the same temperature to end with. I am pretty certain that they don't have to be - but the author of the problem set it this way for some reason I'm missing (my guess). My reasoning: Put 100 K and 300 K together for a short time, but not so long that they have the same temperature. Voila! All three bodies have different temperatures. Thanks

 

[TSny]

I am not sure why two of the bodies are at the same temperature to end with.

Hint: Suppose all three bodies have different temperatures. Can you see how it would always be possible to raise the temperature of the hottest of the three?

 

[laser1]

Hint: Suppose all three bodies have different temperatures. Can you see how it would always be possible to raise the temperature of the hottest of the three?

Ah yeah fair because you could always increase it by using a Carnot engine and raise the temp. due to work! Thanks